Major Findings: Recruitment for this protocol started April 2010. Collection of the 20 healthy volunteers has been completed. To date 32 children with CP have been enrolled, and we do not anticipate enrolling further subjects. Our major goals this past year was to analyze the clinical outcomes and muscle imaging data. We have also been working closely with our collaborators from Hopkins on the brain imaging data which includes functional connectivity data from rsMRI and DTI and have completed processing all baseline data for 17/20 controls, and 16 children with CP for whom there are good MRI data. Th We are hoping to close out Objective 2 this year, complete data analysis and begin dissemination. I will be presenting an abstract on the functional outcomes at the American Academy for Cerebral Palsy and Developmental Medicine Meeting in October 2015. Proposed course of Work The implicit goal of this work is to determine whether intense reciprocal training of the lower extremities can stimulate sensorimotor pathways in CP to a sufficient degree to effect change in motor coordination and cortical connectivity within and between the sensory and motor areas of the brain. One concern is that the sensory system in CP may be compromised and therefore not as promising an avenue for promoting motor and cortical change. Conversely, it is possible that these areas that have been long deprived or more poorly developed may respond even more dramatically to stimuli than if they were more robust. Given our compliance monitoring in our devices, we may also gain information on dose-response to exercise since it is possible that not all will comply with all exercises or duration of exercises as specified in the protocol. We will also be able to relate patient characteristics such as age, level of involvement, degree of spasticity, etc. to responses from the interventions. In CP, variability in outcomes is often observed across subjects and remains poorly understood. We also anticipate that we will gain fundamental information about the nature of reciprocal coordination in CP and how it relates to motor severity, the integrity of the sensory or motor pathways, or regions such as the cerebellum (assuming we acquire sufficient information on that brain region in our sample). Project Impact Statement: This will be the first reported efficacy trial of both motor-assisted cycling and elliptical training in CP. If results are as anticipated, i.e. reciprocal coordination improves as a result of training, then these findings would warrant further comparison with existing treatments such as BWSTT through clinical trials. If coordination does change, we will also be very interested in determining whether there are concurrent changes in the sensorimotor pathways showing an increase in connectivity as a result of training. The relationship of the initial integrity of sensory and motor pathways to the response from interventions will also be explored to determine whether it may be possible to predict which patients may be most likely to benefit from training that targets the spinal pathways. It is the first study to compare muscle integrity before and after strength training in CP.